EARLY AND LATE PRESENTATION OF THE OVARIAN HYPERSTIMULATION SYNDROME - 2 DISTINCT ENTITIES WITH DIFFERENT RISK-FACTORS

This study was designed to identify clinical predictors for early and late ovarian hyperstimulation syndrome (OHSS). A retrospective analysi s of all 592 in-vitro fertilization (IVF) cycles from the programme's inception in 1988 up to March 1993 was performed. Six patients (1.0% o f cycles) had moderate or severe OHSS presenting 3-7 days post-human c horionic gonadotrophin (HCG), and four patients (0.7% of cycles) had s evere OHSS presenting 12-17 days post-HCG. No patient with early OHSS went on to develop late OHSS, and no patient with late OHSS had demons trated early OHSS. Stepwise logistic regression showed that early OHSS was predicted by the number of oocytes retrieved (range 18-46) (P = 0 .0001) and the oestradiol concentration on the day HCG was given (rang e 12 122-24 454 pmol/l) (P = 0.0003). Late OHSS was predicted by the n umber of gestational sacs (range 2-3) on ultrasound 4 weeks after embr yo transfer (P = 0.0001) but not by the number of oocytes or oestradio l. Early OHSS was an acute effect of the HCG administered prior to egg retrieval in women with high oestradiol and larger numbers of follicl es (range 22-51). Late OHSS was induced by the rising serum concentrat ion of HCG produced by the early pregnancy, and in this series of case s it was associated only with multiple gestation.